METHOD FOR SEPARATING PHENOL FROM STREAMS CONTAINING PHENOL THAT HAVE BEEN OBTAINED DURING THE PRODUCTION OF BISPHENOL A

摘要

The invention relates to a method for the continuous separation of phenol from a sub-stream obtained during the production of bisphenol A, containing 40 to 90 wt. % phenol, 5 to 40 wt. % bisphenol A, in addition to 5 to 40 wt. % minor constituents, which occur during the conversion of phenol and acetone to bisphenol A. According to said method, a) the sub-stream is fed to a distillation column containing at least 5 theoretical separation stages, b) phenol is stripped via the head in the distillation column, c) a first part of the bottom product is evacuated from the process, and d) a second part of the bottom product is continuously transferred into a retention container, in which the minor constituents that are contained in the bottom product are at least partially isomerised at temperatures of 190 °C and a hydrodynamic residence time of at least 120 min, in the presence of an acidic catalyst and are then fed back to the distillation column. The mass flux of the part of the bottom product that is fed to the retention container amounts to more than 30 % of the mass flux of the sub-stream that is introduced into the column in step a).